This research provides the first support for a possible psychological universal: human beings around the world derive emotional benefits from using their financial resources to help others (prosocial spending). Analyzing survey data from 136 countries, we show that prosocial spending is consistently associated with greater happiness. To test for causality, we conduct experiments within two very different countries (Canada and Uganda) and show that spending money on others has a consistent, causal impact on happiness. In contrast to traditional economic thought--which places self-interest as the guiding principle of human motivation--our findings suggest that the reward experienced from helping others may be deeply ingrained in human nature, emerging in diverse cultural and economic context...